Chandipura, Kern Canyon, Mokola and Piry mRNA species will be isolated and purified on polyacrylamide gels. These RNA species will be used in annealing experiments with corresponding DI particle RNAs in order to determine the genetic loci of these particles. Determination of the size of DI particle RNA required for interference will be made by measuring the sensitivity of interfering ability to ultraviolet light. Examination of the 5' terminal nucleotide sequences of DI particle RNAs generated by VSV Indiana and generally conserved in these particles will be carried out. We demonstrated that the unique DI particle generated by a heat resistant (HR) mutant which contained the 3' terminus of the viral genome, interfered heterotypically with one subgroup of New Jersey VSV but not with the other. In order to test whether there is a difference in the 3' termini of these viral RNAs transcriptase assays will be carried out with reconstituted viral cores of new subgroup and L protein of the other subgroup.